Hello, webmasters.

I've been having issues installing wordpress and plug-in on my new wordpress site. Whenever I try installing either theme or plug-in, it returns the error as it's shown on the screenshots below.

I, initially, thought the problem is because I used the latest version of wodpress which might be due to the fact some themes and plug-ins are not compatible with the latest version yet. I now decided to downgrade it to the oldest version (4.9.10) of WordPress, but I'm still experiencing the same error.
Please how can I resolve this?
I'v explored all the possible solutions I now, but now positive result yet.

Thanks

Modified: Please note that I was not installing the theme or plug-in as external files, I was trying to install them directly from my dashboard.

Update: I have fixed it. Thanks

Where did you get the theme file ?

PrinceOgun:
Where did you get the theme file ?

From the WordPress dashboard. I have fixed it. Thanks for your input bro